"Because of the varying capacities and inclinations of beings the Buddhas have taught various methods of practice and philosophy. If we follow one of these and yet belittle others, we abandon the Dharma and consequently the Buddhas as well.
Question: Does Your Holiness think that the various world religions were founded by emanations of the Buddhas manifesting in accordance with the mentalities of the specific societies?
Answer: This is highly possible. The founder of any religion could be an emanation of a particular Buddha. It is for this very reason that we should treat all religions with deep respect.
Question: Then why do these different religions so often fight with one another?
Answer: This is a different matter. For a truly religious person there is never any basis for quarrel or dispute. Yet it is a fact that there have been so-called religious wars. However, the people involved in these were not practising religion but were merely using religion as an instrument of power. The actual motivation was selfish, not spiritual. Religious wars are not a question of contradictions between religions at all.
Leaving aside the disparities between the doctrines of different religions, there are many ostensible contradictions within the teachings of Buddha.
So what is a Buddha's purpose in teaching? It is neither to boast nor to demonstrate how much he knows, but to benefit others. Also, he is not concerned with those of his generation alone but with many generations and different kinds of people. Therefore, his teachings must have many different levels of meaning, some often seemingly contradictory. Knowing this, there is never a valid reason for religious quarrels and disputes."
His Holiness the Dalai Lama
http://www.lamayeshe.com/index.php?sect=article&id=415